As a high-performance permanent magnet, rare-earth magnets such as Sm—Co based magnets and Nd—Fe—B based magnets are known and being used for electric appliances such as motors, power generators and the like. The electric appliances using a permanent magnet are increasingly demanded to reduce size, weight and power consumption, and therefore to comply with the demands, the permanent magnets are demanded to have higher performance. When the permanent magnet is used for motors of hybrid electric vehicles (HEV) and electric vehicles (EV), the permanent magnet is demanded to have heat resistance.
For motors for the HEV and EV, there is used a permanent magnet with its heat resistance improved by partly substituting the Nd of the Nd—Fe—B based magnet with Dy. Since the Dy is one of rare elements, there are demands for a permanent magnet not using the Dy. As highly efficient motors and power generators, there are known variable magnetic flux motors and variable magnetic flux generators using two types of magnets such as a variable magnet and a stationary magnet. For the variable magnet, Al—Ni—Co based magnets and Fe—Cr—Co based magnets are used. To provide the variable magnetic flux motors and the variable magnetic flux generators with high performance and high efficiency, it is demanded to enhance the coercive force and magnetic flux density of the variable magnets and stationary magnets.
It is known that the Sm—Co based magnet showing excellent heat resistance is a type not using the Dy. It is also considered that it is possible to use as a variable magnet an Sm2Co17 type magnet among the Sm—Co based magnets on the basis of its coercive force exhibiting mechanism and the like.